MORTALITY AND INGROWTH PATTERN OF DIPTEROCARPS IN FOREST RECOVERY IN EAST KALIMANTAN FARIDA H. SUSANTY, ENDANG SUHENDANG , I NENGAH SURATI JAYA2 2 and CECEP KUSMANA3 1Researcher on Dipterocarps Research Center, Samarinda 75119, Indonesia 2Department of Forest Management, Institut Pertanian Bogor (IPB), Bogor 16680, Indonesia 3Department of Silviculture, Institut Pertanian Bogor (IPB), Bogor 16680, Indonesia Received /Accepted 3 May 2013 24 November 2014 ABSTRACT In primary and logged-over natural forest trees conditions tree structure, mortality and ingrowth rates , the such as will vary according to the species characteristic. Quantitative management variables become very important to support yield regulation tools for achieving sustainable forest management. The objective was to determine study mortality and ingrowth rates to formulate biometric characteristic variability Dipterocarps forest in logged-over of forests based on time series The was Labanan, East Kalimantan Province. Permanent data. study site located in measurement within -over were located to represent three , i.e plots logged forest different logging techniques . a) reduced impact logging with diameter limit 50 cm (RIL 50); b RIL 60; c conventional logging; and d) primary forest ) ) as control Total plot permanent area was 48 ha and was measured periodically every 2 years within 17 years after . about logging. For data analysis purpose, trees were divided into Dipterocarps and non-Dipterocarps. two major groups, i.e. Range of mortality rates for all species in logged-over forest were 2.5-29.3% per ha per 2 years which was close very to primary forest at year-5 after logging. While range of ingrowth rate for all species in logged-over forest were 1.3-21.3% per ha per 2 years which were higher than those for the primary forest within 17 years. The mortality and ingrowth rates fluctuation of Dipterocarps species group were different from those of non-Dipterocarps. : Keywords Dipterocarps, ingrowth, logged-over forest, mortality INTRODUCTION Lowland tropical rain forest is a natural forest with trees having typical characteristics, harboring the greatest species diversity in the world (Whitmore 1990; Richards 1996) and having numerous variations of tree's dimensions (Prodan 1968). Lowland tropical rain forests in Southeast Asia are dominated by Dipterocarpaceae (Ashton 1982), therefore, it is often referred to as the Dipterocarp forests. Dipterocarp forest is a tropical rainforest inhabiting type A and type B climate types are a, cove ring Sumatera, Kalimantan, Sulawesi, North Maluku and Papua with the highest layer of forest canopy filled with family Dipterocarpaceae, especially genus Shorea, Dipterocarpus, Dryobalanops Hopea and (Ashton 1982). Dipterocarp forest in West Malesia region is the most productive tropical forest types based on timber value (FAO 2001). In Indonesia, Dipterocarpaceae is the largest contributor (over 25%) to commercial timber forests in decades, with volume of 50-100 m per ha, especially in 3 Kalimantan (Sist . 2003)et al . In primary and logged-over natural forest, the stand stand conditions having differences in structure, species composition, tree density, canopy structure, mortality and ingrowth, will have varied growth rates depending on tree the age after logging (Silva . 1995; Lewis . 2004; et al et al Ishida . 2005). Recovery of a logged-over et al forest happens in a long period after logging (Smith & Nichols 2005), which varies depending on deforestation rate and environmental carrying capacity (Muhdin . 2008). Natural production et al forests in Indonesia have more than 50% of logged-over forests (Ditjen Planologi Kehutanan 2011). Therefore, it is very important to know * Corresponding author : fhsusanty@gmail.com BIOTROPIA Vol. 22 No. 1, 2015: 11 - 23 DOI: 10.11598/btb.2015.22.1.297 11 mailto:fhsusanty@gmail.com BIOTROPIA Vol. 22 No. 1, 2015 12 about the variation of tree characteristics in a log ged-over forest. Biology and ecology information of Dipterocarps is needed as scientific basis for developing effective forest management policies (Naito . 2008).et al Forest biometric characteristics is among quantitative approaches to study the properties or characteristics of forest trees in size (metric) for a specific biological dimension as the user identification by ratio and interval scale (Prodan 1968). Input variables to determine quantitative tools are mostly provided by classical forest inventories on plots (Vanclay 2003; Gourlet- Fleury . 2005). Most of the early biometric et al research are found in studies on plantations and temperate forests that do not have such complexity as tropical forests. The heterogeneity and complexity of obstacles occur in the forms of diversity and variation of conditions as well as limitations or lack of long term data observation. Average rate of mortality and its correlations to several reliable and measurable variables in size or site characteristics as input factors mostly determine the mortality model (Keister 1972; Hamilton & Edwards 1976; Monserud 1976; Hamilton 1994; Monserud & Sterba 1999; cited Flewelling & Monserud 2002). According to Chertov . (2005), a new paradigm in achieving et al sustainable f orest management requires prediction of effective growth forest tree dynamics involving aspects of ecological characteristics. To achieve sustainable forest management, preparation of quantitative management tools such as yield regulation models becomes very important. Important variables needed to build the models are mortality and ingrowth rates of forest trees. This aimed to determine study mortality and ingrowth rates of Dipterocarps and non-Dipterocarps spesies groups for 17 years after being logged, which rates will be used to formulat biometric characteristics variability e of Dipterocarp forest in logged-over forests based on time series data. MATERIALS AND METHODS Study Site This study was carried out at Labanan research forest station (1˚49'-2˚10' N and 116˚7'-117˚27' E) located in Berau Region, East Kalimantan Province. According to Schmidt and Ferguson climate classification (1951), the study site was within type B climate (Q = 14.3–33.3%). Based on Koppen system classification the study site was within type AFA climate with many rainy days over in a year with mean annual precipitation about 1,800-3,000 mm/year. The highest monthly mean precipitation happened in January (242.5 mm) and the lowest is in August (90.9 mm). Maximum temperature rate happens in September and November (35 ºC) and the lowest was in February and August (21 ºC), with average temperature of 26 ºC. The study site was located at 500 m above sea level (asl) and it was a relatively hilly forest. Soil type in Labanan research forest station consisted of Ultisol (87.3%), Entisol (10.7%) and Incenptisol (2.0%). Labanan research forest station as a low land tropical forest is dominated by family Dipterocarpaceae, consisted of 7 genera i.e. Anisoptera, Cotylelobium, Dipterocarpus, Dryobalanops, Parashorea, Shorea Vatica and . Besides family Dipterocarpaceae, other dominant genera are also present in Labanan research forest station such as Sapotaceae, Meliaceae, Moraceae, Ebenaceae, Sapindaceae Leguminaceae and . Among landscapes at the Labanan research forest station was a swamp forest dominated by and Lophopetalum Shorea balangeran (Saridan and Susanty 2005. Figure 1. Study site-Labanan research forest station, Berau, East Kalimantan Province Mortality and ingrowth pattern of dipterocarps in forest recovery in East Kalimantan Farida H. Susanty – et al. Data Collecting Permanent plots were set up in the logged-over forest as well as in the primary forest. The size of each plot was 200x200 m (4 ha) which was divided into 4 square subplots with size of 100x100 m (1 ha). The permanent plots were built in 4 condition variations with total area of 48 ha. Measurements were carried out by census method for all species with limit diameter of 10 cm including number of trees, tree species, stem diameter (diameter at breast height or 20 cm above buttresses) and number of dead trees. Repeated measurements were performed every two years. Reduced impact logging can be defined as logging technique to minimize environment impact on forest trees and soils (Dykstra 2008). This technique is needed to preserve ecological aspect of forest trees and to ensure sustainable yield of production forest in the future. Data used in this study were data collected from 1990 to 2008. Treatments applied on research plots were as follows: a) RIL 50: reduced impact logging techniques with limit diameter of 50 cm, skid trail planning was based on contour maps and tree position as well as supervision of tree felling and skidding (3 plots). b) RIL 60: reduced impact logging techniques with limit diameter of 60 cm, skid trail planning was based on contour maps and tree position as well as supervision of tree felling and skidding (3 plots). c) CNV: conventional logging techniques with limit diameter of 60 cm, no skid trail planning, conducted without considering contour line maps or tree position, felling was done by loggers experiences (3 plots). d) PF: primary forest as controls (3 plots). Data Analysis Data organization was carried out using database software Microsoft Visual FoxPro 9.0, while data analysis was performed by using spreadsheet and SPSS 15.0. Data were analyzed based on tree density and tree structure (stems per ha) as well as basal area (m per ha) with two major 2 species groupings e.g. Dipterocarps and non- Dipterocarps species. Calculations of mortality and ingrowth rates were performed every 2 years. Residual tree characteristics assessment was done by comparing variations in forest conditions by using different test mean values (t-test), analysis of variance (ANOVA) and regression analysis. Regression equation tested was linear equations, polynomials, exponential and logarithmic. Criteria used for selecting the best equation were based on the regression coefficient (r), determination coefficient (R ) and the highest 2 value of the smallest standard error (SE) (Steel & Torrie 1995) RESULTS AND DISCUSSION Tree Density The dynamics of logged-over forest within 17 years were represented by number of trees per hectare and basal area per hectare against tree fluctuations after-log ging using different logging techniques (Fig. 2). Mean values of tree density at the initial conditions (pre-harvest) were compared using t-test and the results showed no significant differences in all study plots (t